"Anabolic steroids" is the familiar name for synthetic substances related to the male sex hormones (e.g., testosterone). They promote the growth of skeletal muscle (anabolic effects) and the development of male sexual characteristics (androgenic effects) in both males and females. The term "anabolic steroids" will be used throughout this book because of its familiarity, although the proper term for these compounds is "anabolic-androgenic steroids." As discussed in this book, the primary medical uses of these compounds are to treat delayed puberty, some types of impotence, and wasting of the body caused by HIV infection or other diseases. However, steroids can also be abused and this has become so widespread in athletics that it has affected the outcome of sports contests. Illicit steroids are often sold at gyms, competitions, and through mail order operations after being smuggled into this country. This book presents important information related to this problem.